1. Field of the Invention
This patent application relates to the field of building construction equipment and, more specifically, to a new formwork for manufacturing concrete structures, pillars, or square or rectangular columns.
2. Description of Related Art
Formworks in the prior art are manufactured with wood panels and have a number of drawbacks, including the cost of raw materials, the need of preparing and adapting the various form boards, the instability of materials over time, a high weight, and joints with other formworks that are difficult to perform.
Formworks in plastic materials have been used with increased frequency and are based on modular elements obtained by molding a plastic material. Plastic formworks essentially comprise a plurality of retaining panels, in contact with and retaining the concrete on one side, and having stiffening ribs on the edges and transversally on the opposite side. The ribs of these plastic formwork panelss, both edge and transversal ribs, comprise a single wall perpendicular to the retaining panel. Advantages of these plastic formworks are low weight, durability over time, and easy joining with other formwork panelss.
In order to obtain plastic formworks with sufficient resistance to deformation, it is necessary to produce retaining panels of suitable thickness and/or a very high number of ribs both at the edges and in a transversal position. These ribs must also have a suitable thickness. This involves the use of a large amount of plastic material with a high production cost.
The wood formworks in the prior art used for manufacturing concrete structures, either reinforced or not reinforced, require the use of metallic retaining rods of a small diameter, to prevent the opening of the formwork due to the pressure of the poured concrete. These containing rods are positioned across the cast concrete and the parallel panels, and are retained by traction plates positioned against the panels in order to avoid their separation. Suitable spacers, made from tubular elements with enlarged ends, are positioned between two parallel panels in order to achieve a predetermined distance.
A traction plate in the prior art applies counterbalancing pressure on a panel of the wood formwork panel but may flex the panel or otherwise damage it. When the formworks are made of plastic material, the iron traction plates may damage the formwork ribs and otherwise distribute stress only over a small area. In any event, the formworks ribs must be manufactured of an appropriate thickness, in order to avoid a flexing of the panel due to the pressure of the traction plates, to possible collisions, or to axial or non-axial stresses.